Merge remote branch 'tip/x86/tsc' into fortglx/2.6.38/tip/x86/tsc

Conflicts:
	Documentation/kernel-parameters.txt

2 files changed, 10 insertions, 6 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 92e83e53148f..c7c8eca5b2b3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2467,12 +2467,13 @@ and is between 256 and 4096 characters. It is defined in the file
                         to facilitate early boot debugging.
                         See also Documentation/trace/events.txt
 
-        tsc=            Disable clocksource-must-verify flag for TSC.
+        tsc=            Disable clocksource stability checks for TSC.
                         Format: <string>
                         [x86] reliable: mark tsc clocksource as reliable, this
-                        disables clocksource verification at runtime.
-                        Used to enable high-resolution timer mode on older
-                        hardware, and in virtualized environment.
+                        disables clocksource verification at runtime, as well
+                        as the stability checks done at bootup. Used to enable
+                        high-resolution timer mode on older hardware, and in
+                        virtualized environment.
                         [x86] noirqtime: Do not use TSC to do irq accounting.
                         Used to run time disable IRQ_TIME_ACCOUNTING on any
                         platforms where RDTSC is slow and this accounting
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 0c40d8b72416..bb64beb301d9 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -872,6 +872,9 @@ __cpuinit int unsynchronized_tsc(void)
 
         if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
                 return 0;
+
+        if (tsc_clocksource_reliable)
+                return 0;
         /*
          * Intel systems are normally all synchronized.
          * Exceptions must mark TSC as unstable:
@@ -879,10 +882,10 @@ __cpuinit int unsynchronized_tsc(void)
         if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
                 /* assume multi socket systems are not synchronized: */
                 if (num_possible_cpus() > 1)
-                        tsc_unstable = 1;
+                        return 1;
         }
 
-        return tsc_unstable;
+        return 0;
 }
 
 static void __init init_tsc_clocksource(void)